Nickel,copper and cobalt distribution and equilibria in Anglo Platinum furnace slags

Abstract

Base metals (nickel, copper and cobalt) are recovered as part of the smelting and refining process operated by Anglo Platinum in South Africa. This study focuses on the losses of these metals to furnace slag and the effect of changing the furnace feed to include or exclude recycled oxidising converter slag. A combination of electron microbeam and Mössbauer techniques were used to characterise the base metal distribution in the slag, the variation of losses with depth in the slag bath, and the oxygen activity in the slag. Base metal dissolution into the slag is underestimated if bulk matte–slag equilibrium is assumed; predictions are closer to the observed extent of dissolution if equilibrium between entrained matte and slag is assumed, for oxygen activity controlled by the Fe³⁺(slag)/Fe²⁺(slag) or FeO(slag)/Fe(matte) buffers.